Typical operating systems (e.g., windows-based systems by Microsoft, Sun Solaris™, Linux™, MacOS by Apple Computer, Unix, etc.) provide a resource manager. The resource manager shares the resources of a computer system with the applications requesting use of the resources. Typical resources that are managed by a resource manager include processors, disk space, memory, peripheral devices, etc. For example, if two applications request to use the printer, the resource manager determines which application uses the printer first by placing requests into a queue. In this example, the applications and the printer may be local to one system, and the local printer may be the only printer available to the applications.
In a distributed system, computer systems may be located in multiple locations throughout a private or public network. The computer systems within a distributed system may be considered a client, a server, or act as a client and server in certain situations. The client is typically the computer system that requests a service or resource, while the server is a computer system that shares a resource or performs a service (hereinafter, the use of the term “resource” is intended to refer to resources or services). A distributed system is useful because the distributed system allows the load created from the client requests to be distributed among a number of servers. The distributed system allows a client request to be handled by one of the number of servers.
Several methods are currently used to provide the location of a server where the requested resource may be found. These methods include using directory services, advertising (e.g., broadcasting), and querying (e.g., unicast, multicast, etc.). The current methods may provide a one-to-one mapping of a client and a server that handles the request of the client. With this method, several servers may be available to satisfy requests, but individual clients are mapped directly to specific servers. Another method, for example, may send a request out to the network, where servers that are listening for requests respond.
As discussed above, the server may handle a client's request for a resource using a one-to-one mapping. For example, a client, Client X, may have an object, Object A, that needs to be stored. Client X may be mapped, using a one-to-one mapping, with Server Z. In this distributed system, Client X may send a request to Server Z to store Object A. Several possibilities may occur. Server Z may reply indicating that space is available and Object A may be stored on Server Z. Server Z may reply indicating that space is not available, and Object A cannot be stored on Server Z. Server Z may reply indicating that the Server Z is busy, and the request is handled later. Server Z may not reply. In this type of system, the server typically is prepared for the specific types of requests that a client may make, and has a large amount of resource available.